The present invention relates to bicycle frames and, more particularly, bicycle frames in which the control cables extend through the interiors of structural frame members.
In the manufacture of bicycles of the type having control cables for such components as, for example, caliper brakes, it is necessary to provide means for attaching the cables to the structural components of the bicycle frame. In most bicycles of this type, the cables are attached to the exterior of the frame by clips or bands made of such materials as steel or nylon. While such means of attaching cables to bicycle frames are effective and relatively inexpensive, they tend to distract from the aesthetic appearance of the frame. In addition, the location of the cables on the exterior of the frame members may tend to interfere with other components of the bicycle, such as tool compartments, which are also attached to the frame exterior.
In order to eliminate the appearance of cables on the exterior of bicycle frames, attempts have been made to extend the cables through the interiors of tubular frame components. For example, the Artaud French Pat. No. 982,877 shows a bicycle frame in which the top tube consists of a hollow, tubular member having a forward cable outlet at a location near the head tube socket which is attached to the top tube, and a rearward cable outlet adjacent to the seat mast of the bicycle frame. While the internal cable system of this frame eliminates the appearance of the cable on the exterior of the frame components, a new problem is created. There is no provision for the rapid replacement of the cable which extends through the interior of the top tube of that device.
In the event of the excessive wear or breakage of the cable extending through the top tube of that frame, it might be necessary to disassemble the top tube from the head tube and seat bracket in order to expose the interior of the top tube so that a new cable may be guided through the cable outlets. Another possibility of replacing a cable would involve the insertion of a stiff lead wire through the rear cable outlet, along the top tube and out through the forward cable outlet. The end of a replacement cable would then be attached to the end of the wire, and the wire withdrawn back through the top tube and rear cable outlet, thereby drawing the replacement cable after it. Such a replacement method would be time-consuming and frustrating, if it worked at all.
Another disadvantage of internal cable systems typified by the Artaud device is that the forming of openings along the top tube of a bicycle frame tends to weaken the wall of that tube, which would require either that the tube be made of a strong but heavy material such as steel, or that the tube walls be thickened if made of a relatively light material which would also add to the overall weight of the frame.
Accordingly, there is a need for an internal cable system in which the installation and replacement of the cable is a relatively easy process. Furthermore, there is a need for an internal cable system for a bicycle frame in which the structural integrity of the tubes housing the cable is not compromised.